Posterior Short-segment Pedicle Screw Research Articles

Mechanical Analysis of Posterior Pedicle Screw System Placement and Internal Fixation in the Treatment of Lumbar Fractures.

Objective Image segmentation technology is applied to separate a single vertebra from the three-dimensional model of the spine, so as to separate a single vertebra image with smaller error, higher degree of automation, and better results. The objectives are to study the biomechanical characteristics of posterior short-segment pedicle screw fixation by three-dimensional finite element method, analyze the mechanical characteristics of posterior pedicle screw rod fixation system under different factors, and demonstrate the feasibility of its application in the treatment of lumbar fracture. Methods The authors searched the database for articles about the treatment of lumbar spine fracture, screw rod internal fixation system, and its mechanical parameters. The threshold segmentation method based on region segmentation method was used to segment the image, and the three-dimensional finite element model was used to analyze the biomechanical characteristics of different posterior internal fixation for lumbar spine fracture. Results The posterior pedicle internal fixation system for the treatment of multilevel spinal fractures is a mature surgical technique and has fewer postoperative complications. Transpedicle fixation is effective and reliable. It can effectively restore the coronal and sagittal curvature of the vertebral body and restore the stability of the spine better. But the choice of internal fixation method should be individualized based on fracture type, identification of critical and secondary injury sites, and stability assessment. Only after mastering the biomechanical characteristics of the posterior screw rod system for the treatment of lumbar fracture, selecting the appropriate method, and fixing the appropriate movement unit can the best fixation be achieved. Conclusion Threshold method is the most direct and simple image segmentation method. The core technology of thresholding is the selection of threshold, which will affect the final segmentation effect. The most common segmentation method is to calculate the segmentation threshold by histogram. The threshold method has less computation and good segmentation effect for the image with large contrast between background and target. Posterior pedicle screw rod system internal fixation has the advantages of less trauma, good reduction, reliable fixation, and less complications. The design, placement angle and depth of various internal fixation systems, and the number of fixed segments all show different mechanical characteristics. As long as we master the above characteristics, choose the appropriate method and fix the appropriate motor unit, and we can get the best fixation; it can be used as an effective treatment for lumbar fracture.

The radiological outcomes of short-segment pedicle screw fixation combined with transforaminal interbody fusion for treatment of thoracolumbar burst fracture

Objective: This study aims to evaluate radiological outcomes of short-segment pedicle screw fixation with transforaminal interbody fusion (TIF) using bone chip graft for treatment of unstable thoracolumbar burst fracture, Denis type IIB. Subject and method: The data in this study were retrospectively collected from all patients with isolated unstable thoracolumbar burst fractures treated by posterior short segment pedicle screw fixation and TIF from January 2013 to January 2017. All patients were followed up for a minimum time interval of 1 year. For radiologic outcome evaluation, a loss percentage of anterior vertebral body heights (%ABC), vertebral kyphotic angle (VKA) and regional kyphotic angle (RKA) were collected preoperatively, postoperatively and at final follow-up. Result: There were 36 patients who met the inclusion criteria with a mean follow-up duration of 53 months (range, 17-73 months). The mean % ABC, VKA and, RKA at the time of admission were 49.9%, 24.6o and 19.7o, respectively. These values were 17.6%, 11.5o, 8.5o postoperatively, and 27.5%, 14.4° and 14.1° at final follow-up, respe­ctively. Fusion rate at final follow-up was 91.7% based on Bridwell’s criteria. There were 6 patients (16.7%) with hardware failure at final follow-up. Conclusion: Short-segment pedicle screw fixation with TIF using bone chip graft is an effective surgical management for unstable thoracolumbar burst fracture with the acceptable radiological outcomes in Vietnamese patients.

The Use of Crosslinks with Posterior Pedicular Screw Fixation in Lumbar Spondylolisthesis

Abstract Background Pedicle screw instrumentation has gained wide popularity for stabilization of spinal fusions. The use of pedicle screw fixation has increased fusion rates. The placement of segmental pedicle screws and cross-links in short segment posterior pedicle screw constructs has been shown to increase the construct stiffness in some planes. Aim of the Work to evaluate addition of crosslinks to posterior pedicular screw fixation as a modality for surgical management of lumbar spondylolisthesis. Patients and Methods This study included 50 patients with lumbar spondylolisthesis divided into two groups according to the surgical approach used in treatment. One group with Posterolateral fixation by transpedicular screws and rods and the other Group had cross-links added to the posterior construct. Results There was no significant difference in postoperative JOA score between both groups, while comparing mean of preoperative and postoperative JOA scores in each group showed a significant rise of the score in each group after surgery. There was no significant difference in the variables of postoperative sagittal alignment between both groups, while comparing mean of preoperative and postoperative sagittal alignment variables in each group revealed a significant reduction of the disc height percent in both groups, and in slip angle and lumbar lordosis angle in group B. Regarding postoperative rate and degree of improvement in the studied groups, there was no significant difference in the rate and degree of improvement between both groups. Conclusion no appreciable benefit from using cross-links was found in short-segment fixation of lumbar spondylolisthesis, where there’s no or little torsional instability encountered.

Short-segment pedicle screw fixation combined with vertebroplasty for the treatment of Kümmell disease with kyphosis

To explore the clinical effects of posterior short-segment pedicle screw internal fixation combined with vertebroplasty for the treatment of Kümmell disease with kyphosis. Twenty-four patients with Kümmell disease complicated with kyphosis treated by posterior short-segment pedicle screw internal fixation combined with vertebroplasty from January 2016 to December 2018 were retrospectively analyzed, including 6 males and 18 females, aged 63 to 85 (73.1±6.5) years old. The clinical effect was evaluate by visual analogue scale (VAS), Oswestry Disability Index (ODI), the anterior height of injured vertebral body, and the sagittal Cobb angle of the affected segment beforeoperation, at 3 days and final follow up after operation. And the surgical complications were observed. All 24 patients were followed up from 12 to 24 months with an average of (15.5±3.2) months. The VAS score was decreased from 5.21±1.06 preoperatively to 2.38±0.58 at 3 days postoperatively and 1.71±0.75 at final follow-up;ODI was decreased from (50.4±13.5)% preoperatively to (20.9±8.0)% at 3 days postoperatively and (16.7±9.6)% at final follow-up;the anterior height of injured vertebral body was restored from (8.0±4.2) mm before surgery to (18.1±5.0) mm at 3 days after surgery and (16.8±5.1) mm at final follow up;the sagittal Cobb angle of affected segment was decreased from (19.5±6.3)° preoperatively to (7.6±2.1)° at 3 days after surgery and(8.4±1.7)° at final follow-up. VAS, ODI, anterior height of injured vertebral body, and sagittal Cobb angle of affected segment were significantly improved at 3 days after operation and at final follow-up (P<0.05). Two patients had complications, including asymptomaticcement leakage in 1 patient and superficial wound infection in 1 patient. Posterior short-segment pedicle screw internal fixation combined with vertebroplasty for the treatment of Kümmell disease with kyphosis has relatively small surgical trauma, excellent clinical results, good vertebral height recovery, satisfactory correction of kyphotic angle, and fewer complications, etc. It is a safe and effective surgical method to treat Kümmell disease with kyphosis.

Imageology study of correlation loss and its related factors after short-segment pedicle screw reduction and fixation for lumbar fractures

To analyze the correction loss after posterior segmental fixation for lumbar spine fractures and explore the related image factors. Posterior short-segment fixation was received in 48 patients with L2-L4 fractures. There were 32 males and 16 females, with ages of 23 to 60 (45.98±8.20) yeaes. The anterior vertebrae height (AVH), vertebral wedge angle (VWA) of the injured vertebra and local kyphosis angle (LKA) were measured before operation, 1 week after operation and the final follow-up. The loss of segmental discal angle (LoSDA), LKA(LoLKA), AVH(LoAVH) were calculated between 1 week postoperative and the last follow up. Preoperative load-sharing scores(LSS), TLICS scores, and adjacent intervertebral disc injuries (IDIs) were assessed. Then the correlation between the age, follow up time, LSS, TLICS, IDIs and the correction loss was analyzed. The average follow-up was 12 to 18 (16.13±5.39) months. LKA, AVH and VWA at 1 week postoperative and those at the final follow up, were significantly improved compared with those preoperative (P<0.05). In the final follow up, the average LKA(5.70±3.17)° and AVH(4.31±5.95)% correction loss were observed compared with those 1 week postoperative(P<0.05). Otherwise the lose of VWA was not obvious(P>0.05). Univariate analysis showed that the SDA (r=0.706, 0.579, 0.449) and LKA(r=0.715, 0.566, 0.502) correction loss were aggravated with the increase of LSS, TLICS and IDIs, and AVH (r=-0.325, -0.219) correction loss was aggravated with the increase of LSS and TLICS(P<0.05). Multivariate analysis showed that increased LSS scores were all risk factors for segmental disc angle (SDA) loss, LKA correction loss, and AVH correction loss (P<0.05). The angle of adjacent intervertebral discs and anterior height of injured vertebrae were lost statistically after posterior short-segment pedicle screw treatment for lumbar fractures, and multivariate analysis showed that all of them were correlated with load-sharing score.

Short Term Results of Fixation of Unstable Thoracolumbar Fractures with and without Intermediate Screws: A Comparative Study

Background: Posterior short-segment pedicle screw fixation is widely used for unstable thoracolumbar (TL) fractures. Adding a pedicle screw at the fractured vertebrae could significantly improve the stability and decrease the stress on fixation construct. Objective: Compare the efficacy of short segment pedicle screw fixation with and without intermediate screw in correction of the vertebral body height, local kyphosis and maintenance of the correction in the treatment of unstable thoracolumbar spine fractures. Patients and Methods: This study was a prospective cohort study. 40 patients with unstable thoracolumbar fracture were divided randomly into 2 groups according to the surgical method used. In group B, 20 patients underwent fixation via short-segment pedicle screw instrumentation (1 level above and 1 level below the fractured level). In group A, 20 patients received additional screws at the fractured vertebrae. Results: Both groups had significant correction in Cobb angle, anterior body height and local kyphotic angle. However group A had significantly higher correction achieved in Cobb angle (10.35 ± 6.02), anterior body height (1.15 ± 0.50) and local kyphotic angle (13.30 ± 7.54) than group B (3.45 ± 3.94), (0.40 ± 0.41) and (5.05 ± 4.36) respectively. Nevertheless, the differences in VAS score (p=0.759) and ODI (p=0.934) were not significant. Moreover, group A had a significantly lower loss of correction in Cobb angle (p=0.025) after twelve months of follow up. Conclusion: The construct with intermediate screw was associated with not only better correction but also less correction loss after 12 months. However, this was not reflected on clinical outcome.

Retrospective analysis of unstable thoracolumbar fractures treated by postural reduction and posterior short segment pedicle fixation

&lt;p class="abstract"&gt;&lt;strong&gt;Background:&lt;/strong&gt; For unstable dorslolumbar injuries, the controversy in choosing between long versus short segment posterior fixation continues.&lt;/p&gt;&lt;p class="abstract"&gt;&lt;strong&gt;Methods:&lt;/strong&gt; 29 patients (13 males, 16 females) with single level unstable thoracolumbar fracture operated by short segment posterior pedicle screw fixation were evaluated retrospectively in terms of kyphosis correction achieved in immediate post-operative period, loss of kyhposis correction at final follow up and clinical outcome on Denis pain scale and any failure of fixation. Average follow up period was 22.07 months (14-40 months).&lt;strong&gt;&lt;/strong&gt;&lt;/p&gt;&lt;p class="abstract"&gt;&lt;strong&gt;Results:&lt;/strong&gt; Average age of patient was 35.7 years (15-50 years). Mode of injury was fall from height in 27 patients and road traffic accident in 2 patients. 12 fractures were at L1, 9 at D12, 6 at L2 and 2 at L3. Neurologically 11 had paraparesis, 4 complete paraplegia and 14 were without any deficit. Pre-operative kyphotic angle was 23.023±11.14 (8-50 degrees) which improved to 7.03±4.69 (0-18) post operatively. Kyphosis at final follow up was 11.759±5.901 (2-25). Loss of kyphosis correction at final follow up was 4.79±2.042 (2-10 degrees). Load sharing classification score (LSC) was 6.89±1.345 (4-9). Denis pain scale at final follow up was p1 in 11 patients, p2 in 15 patients and p3 in 3 patients. There was no case of implant failure and only one case had kyphosis correction loss of 10 degrees.&lt;/p&gt;&lt;p class="abstract"&gt;&lt;strong&gt;Conclusions:&lt;/strong&gt; Short segment fixation provides stable fixation with good results and there is no correlation between LSC and fixation failure.&lt;/p&gt;

Outcome of Pedicular Fixation of Unstable Dorsolumbar Fractures

Background: The spine is made of 33 individual bones stacked one on top of the other. This spinal column provides the main support for your body, allowing you to stand upright, bend, and twist as well as protecting the spinal cord from injury. Objective: The aim of this study was to evaluate the post-operative clinical outcome of transpedicular screw and rod fixation in unstable thoracolumbar fractures by using Mc Nab’s criteria in patients collected from Sohag General Hospital and Sohag University Hospital. Patients and methods: A prospective study included patients admitted to Orthopedic and Traumatology Department of Sohag General Hospital suffering from unstable fracture of thoracolumbar area. The study was conducted on twenty patients suffering from thoracolumbar fractures attending to Department of Orthopedics and Traumatology, Sohag University Hospitals, Sohag General Hospital and Al-Azhar University Hospitals from June 2018 till December 2018. Results: In comparison between cases, which conserved and those operated as regard vertebral height loss, angle of kyphosis, oswestry disability index and visual analogue score, we found that p value was not significant in these parameters and its value was 0.15, 0.46, 0.15, and 0.88 respectively. Which means that decision making correlated to patient score. As regards type of operative fixation done, there were non-significant comparison between type of fixation done and the mentioned parameters. All changes in the parameters explain that these parameters correlate with TLICS and prove the validity of this classification. Conclusion: Posterior short segment pedicle screw fixation is good and enough for treatment of thoracolumber fractures (burst fracture) when neurological condition of the patients is intact.

Percutaneous posterior short-segment pedicle screw fixation combined with vertebroplasty for stage III Kümmell's disease without neurological deficit

Objective To investigate the clinical efficacy of percutaneous posterior short-segment pedicle screw fixation combined with vertebroplasty for stage III Kummell's disease without neurological deficit. Methods A retrospective case series study was conducted to analyze the clinical data of 36 patients with stage III Kummell's disease without nerve injury admitted to Xiaoshan Hospital of Traditional Chinese Medicine from January 2012 to January 2017. There were 10 males and 26 females, aged 55-75 years, with an average of 67.5 years. The injuried vertebrae were located at T11 in 9 patients, at T12 in 12, at L1 in 10 and at L2 in 5. The course of disease ranged from 6 to 48 months, with an average of 28.5 months. X-ray, CT and MRI were performed before operation. All patients underwent percutaneous posterior short-segment pedicle screw fixation combined with vertebroplasty. The operation time, intraoperative bleeding volume, complications, visual analogue scale (VAS), Oswestry dysfunction index (ODI) and sagittal Cobb angle of the injured vertebrae were recorded before operation, 1 week after operation and at the last follow-up. Results All patients were followed up for an average of 32.5 months (range, 12-48 months). Operation time ranged from 0.6 to 1.5 hours[(1.1±0.4)hours]. The intraoperative blood loss was 50-90 ml [(62.5±17.5)ml]. There was no internal fixation failure or fracture of adjacent vertebra. The VAS was improved from preoperative (8.6±0.4)points to (2.5±0.7)points one week after operation and (2.9±0.7)points at the last follow-up (P<0.05). The ODI was improved from preoperative 68.2±3.9 to 22.7±4.3 one week after operation and 25.3±4.8 at the last follow-up (P<0.05). The Cobb angle was improved from preoperative (24.3±9.3)° to (8.6±3.2)° 1 week after operation and (10.5±4.1)° at the last follow-up (P<0.05). Conclusion For stage III Kummell's disease without neurological deficit, percutaneous posterior short-segment pedicle screw fixation combined with vertebroplasty can significantly relieve pain, improve spinal function and maintain spinal stability. Key words: Spinal fractures; Internal fixators; Vertebroplasty; Kummell's disease

Posterior short-segment fixation with transforaminal lumbar interbody fusion for the treatment of unstable lower lumbar fracture

Background: The objective of this study was to evaluate the clinical and radiographic results of posterior short-segment pedicle screw fixation and transforaminal lumbar interbody fusion (TLIF) in selected types of lower lumbar fractures. Methods: Twenty-seven patients with lower lumbar fractures were enrolled in this study. Demographic data, neurologic grade, anterior vertebral body heights, vertebral body translation, segmental Cobb angle, and management-related complications were assessed. The minimum follow-up period was 2 yr. Results: Twenty male patients and seven female patients underwent the procedure, with a mean operative time of 182 min. Mean blood loss was 588 mL. The mean preoperative local kyphotic angle was 9.5 degrees that improved to 2.5 degrees postoperatively. The loss of correction was insignificant at the final follow-up. The preoperative percentage of height lost improved from a mean of 52.5% to a mean of 89.05% postoperatively, and at last follow-up no loss of correction in height was noted compared to the postoperative results. No pseudarthrosis or metal failure was detected. All patients who were Frankle E on admission remained neurologically intact. Conclusions: Posterior short-segment fixation with pedicle screw fixation augmented with TLIF might be a possible choice for selected patients with unstable lower lumbar fractures, particularly in split fractures, burst fractures with a reversed cortex sign, and traumatic spondylolisthesis.

Modified Posterior Short-Segment Pedicle Screw Instrumentation for Lumbar Burst Fractures with Incomplete Neurological Deficit

We have introduced a method of modified posterior short-segment pedicle screw fixation and evaluated its clinical effects in treating lumbar burst fractures with incomplete neurological deficits. The data from 22 patients with lumbar burst fracture and incomplete neurological deficits who had undergone modified posterior short-segment instrumentation with Schanz screw fixation from January 2012 to February 2018 in our clinic were evaluated in the present retrospective study. All Schanz screws were implanted in an oblique downward direction into the vertebrae above and below the injured vertebra (insertion depth, 90%-100%). The implants were removed ∼1 year after surgery. Neurological function, back pain, anterior and posterior body height ratio, kyphosis angle, percentage of canal compromise, fracture severity, and treatment-related complications were evaluated. Technical success was achieved in all 22 patients. No infection, instrument loosening or failure, or breakage was observed. Statistically significant improvements with regard to the anterior body height (P < 0.05) and posterior body height (P < 0.05) ratios, kyphosis angle, and percentage of canal compromise (P < 0.05) were observed at 1 week postoperatively or the final follow-up visit. No correction loss had occurred at the final follow-up examination. Postoperatively, all patients with neurological deficits had functional improvement equivalent to ≥1 grade on the American Spinal Injury Association impairment scale and fracture union. Back pain was greatly improved postoperatively. Short-segment Schanz screw fixation implanted in an oblique downward direction seems to be a promising method for lumbar burst fractures with incomplete neurological deficits because it provided good clinical and radiographic outcomes.

Short same segment fixation versus short segment fixation in postoperative correction of kyphosis and pain reduction in thoracolumbar spine fractures

Abstract Introduction: Posterior short segment pedicle screw fixation is considered the most common way for management of unstable thoracolumbar spine fracture. This study is aiming to evaluate the efficacy of both posterior short same segment and posterior short segment pedicle screw fixation on postoperative kyphotic angle and pain dense score in thoracolumbar fractures. Methods: This is a Prospective study of 32 patients with single level thoracolumbar spine fracture between June 2011 and May 2014. Patients were divided randomly into 2 groups, one of them was submitted to short same segment posterior pedicle screw fixation with mean age 31.25+9.25ys, while the other group submitted to short segment posterior pedicle screw fixation with mean age 29.18+9.65ys. Cobb method and Denis work scale were used to assess kyphotic angle and pain score respectively on admission, during follow up period and after one year postoperatively. Results: The short same segment type of operation showed improvement in correction in kyphotic angle deformity at the end of follow up period although this improvement was not statistically significant compared to short segment type. The short same segment patients showed statistically significant improvement as regard pain Denis score among those patients treated by short segment fixation. Conclusion: In this study short same segment posterior pedicle screw fixation is more efficient in postoperative pain reduction than short segment posterior pedicle screw fixation.

Treatment of unstable thoracolumbar fractures through short segment pedicle screw fixation techniques using pedicle fixation at the level of the fracture: a finite element analysis.

ObjectiveTo compare the von Mises stresses of the internal fixation devices among different short segment pedicle screw fixation techniques to treat thoracic 12 vertebral fractures, especially the mono-segment pedicle screw fixation and intermediate unilateral pedicle screw fixation techniques.MethodsFinite element methods were utilised to investigate the biomechanical comparison of the four posterior short segment pedicle screw fixation techniques (S4+2: traditional short-segment 4 pedicle screw fixation [SPSF]; M4+2: mono-segment pedicle screw fixation; I6+2: intermediate bilateral pedicle screw fixation; and I5+2: intermediate unilateral pedicle screw fixation).ResultsThe range of motion (ROM) in flexion, axial rotation, and lateral bending was the smallest in the I6+2 fixation model, followed by the I5+2 and S4+2 fixation models, but lateral bending was the largest in the M4+2 fixation model. The maximal stress of the upper pedicle screw is larger than the lower pedicle screw in S4+2 and M4+2. The largest maximal von Mises stress was observed in the upper pedicle screw in the S4+2 and M4+2 fixation models and in the lower pedicle screw in the I6+2 and I5+2 fixation models. The values of the largest maximal von Mises stress of the pedicle screws and rods during all states of motion were 263.1 MPa and 304.5 MPa in the S4+2 fixation model, 291.6 MPa and 340.5 MPa in the M4+2 fixation model, 182.9 MPa and 263.2 MPa in the I6+2 fixation model, and 269.3 MPa and 383.7 MPa in the I5+2 fixation model, respectively. Comparing the stress between different spinal loadings, the maximal von Mises stress of the implants were observed in flexion in all implanted models.ConclusionAdditional bilateral pedicle screws at the level of the fracture to SPSF may result in a stiffer construct and less von Mises stress for pedicle screws and rods. The largest maximal von Mises stress of the pedicle screws during all states of motion were observed in the mono-segment pedicle screw fixation technique.

Posterior short segment pedicle screw fixation and TLIF for the treatment of unstable thoracolumbar/lumbar fracture

BackgroundCurrently, Posterior Short Segment Pedicle Screw Fixation is a popular procedure for treating unstable thoracolumbar/lumbar burst fracture. But progressive kyphosis and a high rate of hardware failure because of lack of the anterior column support remains a concern. The efficacy of different methods remains debatable and each technique has its advantages and disadvantages.MethodsA consecutive series of 20 patients with isolated thoracolumbar/lumbar burst fractures were treated by posterior short segment pedicle screw fixation and transforaminal thoracolumbar/lumbar interbody fusion (TLIF) between January 2005 and December 2007. All patients were followed up for a minimum of 2 years. Demographic data, neurologic status, anterior vertebral body heights, segmental Cobb angle and treatment-related complications were evaluated.ResultsThe mean operative time was 167 minutes (range, 150–220). Blood loss was 450 ~ 1200 ml, an average of 820 ml. All patients recovered with solid fusion of the intervertebral bone graft, without main complications like misplacement of the pedicle screw, nerve or vessel lesion or hard ware failure. The post-operative radiographs demonstrated a good fracture reduction and it was well maintained until the bone graft fusion. Neurological recovery of one to three Frankel grade was seen in 14 patients with partial neurological deficit, three grades of improvement was seen in one patient, two grades of improvement was observed in 6 patients and one grade of improvement was found in 6 patients. All the 6 patients with no paraplegia on admission remained neurological intact, and in one patient with Frankel D on admission no improvement was observed.ConclusionPosterior short-segment pedicle fixation in conjunction with TLIF seems to be a feasible option in the management of selected thoracolumbar/lumbar burst fractures, thereby addressing all the three columns through a single approach with less trauma and good results.

Posterior short-segment instrumentation without fusion for treatment of thoracolumbar compression fractures

Objective To investigate the clinical effect of posterior short-segment pedicle screw reduction and fixation without fusion in treatment of thoracolumbar mono-segmental compression fractures.Methods Thirty cases of thoracolumbar mono-segmental compression fractures admitted from January 2009 to February 2010 were assigned to single posterior pedicle screw fixation (screw group,n =15) and posterior pedicle screw fixation with posterolateral fusion (fusion group,n =15) according to random number table.Clinical results in the two groups were assessed based on Cobb' s angle,anterior vertebral body height ratio (％) and Oswestry disability index (ODI) before operation,after operation,prior to the removal of implant and at the latest follow-up.Results All the cases were followed up for average 24 months.Both operation time and blood loss were less in screw group than in fusion group [(76.58 ±12.67) min vs (116.29 ± 17.45) min,P ＜ 0.01 ; (287.54 ± 30.76) ml vs (480.34 ± 100.54) ml,P ＜0.01],whereas there were no statistical differences between the two groups in aspects of Cobb' s angle and anterior vertebral body height ratio before and after operation,prior to the removal of implant as well as at the latest follow-up.Moreover,no statistical difference of ODI was noted between the two groups prior to the removal of implant and at the latest follow-up.Conclusion Posterior pedicle screw fixation without bone grafting achieves similar effects with pedicle screw fixation with bone grafting. Key words: Thoracic vertebrae ; Lumbar vertebrae; Internal fixators

Posterior short-segment instrumentation without fusion for severe thoracolumbar burst fractures

Objective To evaluate the clinical efficacy of treatment of severe thoracolumbar burst fractures by posterior short-segment instrumentation without spinal fusion and assess radiographic imaging and function recovery after surgery.Methods Thirty-eight patients with severe monosegmental thoracolumbar burst fractures treated between July 2011 and March 2013 were analyzed retrospectively.Operation procedures were posterior short-segment pedicle screw distraction reduction and fixation combined with screw insertion to the injured vertebrae and calcium sulphate augmentation.In addition,there was no need for posterolateral interbody fusion.X-ray and CT were performed before and after operation to evaluate local kyphotic angle,anterior fractured vertebral body height and canal encroachment.Visual analogue scale (VAS) and Oswestry disability index (ODI) were assessed before and after operation as well as in follow-up.Results All patients were followed up for average 14 months (range,3-20 months).Local kyphotic angle was (21.2 ±4.3)° before operation,(3.5 ± 1.8)°immediately after operation,and (4.8 ± 2.7) ° in final follow-up.Relative anterior vertebral height was (54.8 ± 14.6)％ before operation,(91.7 ± 8.0)％ after operation,and (87.2 ± 6.0)％ in final follow-up.Mean canal encroachment was (48.0 ± 4.5)％ preoperatively,(23.8 ± 7.8)％postoperatively,and (8.8 ± 4.6) ％ in final follow-up.In final follow-up,six patients with American Spinal Injury Association (ASIA) grade C on admission showed improvement to grade D (n =2) and grade E (n =4) ; 10 patients with ASIA grade E on admission showed improvement to grade E; 22 patients with grade E had no changes.ODI and VAS scored 15.5 ±8.8 and 2.3 ±0.8 in final follow-up with substantial improvement from those before operation (P ＜ 0.01).Complications from internal fixation were not found during follow-up.Conclusion Posterior short-segment fixation without fusion is one of the foremost effective methods for severe thoracolumbar burst fractures,for it can effectively restore the sagittal spinal alignment and the fractured vertebral body height. Key words: Spinal fractures; Thoracic vertebrae; Lumbar vertebrae; Fracture fixation,internal; Non-fusion

Percutaneous augmented instrumentation of unstable thoracolumbar burst fractures: our experience in preventing cement leakage

To the Editor, It was with great interest that we read the article by N. Rahamimov et al., “Percutaneous augmented instrumentation of unstable thoracolumbar burst fractures,” published in the 2011 December issue of European Spine Journal [1]. This is a well-prepared article, which introduces a novel approach, combining percutaneous posterior short-segment pedicle screw augmentation with polymethylmethacrylate (PMMA) and fractured vertebra kyphoplasty to treat unstable thoracolumbar burst fractures. The kyphoplasty mentioned in the article yielded a high ratio of cement leakage (52/52) mainly through fracture line or segmental veins and caused three cases of PMMA pulmonary emboli. In our experience, the risk of cement leakage can be avoided with some good manners [2–4]. The higher viscosity PMMA injected is the key factor to prevent cement leakage. In the procedure, we control ideal level of viscosity when the cement is not runny any more, becomes doughy, does not stick to the fingers and can stand erect at the tip of the bone cement inserter when pushed out, it is considered to be able to block mostly segmental veins. For the fracture line in the anterior wall, small amounts of middle- or late-stage bone cement in the dough phase are used to block the defect to protect against anterior leakage firstly. After the cement has solidified, late-stage bone cement in the paste phase or early stage bone cement in the dough phase is applied to allow the filling to diffuse evenly. For patients with damaged posterior wall, the filling process is stopped as soon as the bone cement reaches the lateral margin or when one-fourth of the distance to the posterior wall of vertebra left under continuous fluoroscopic monitoring (Figs. 1, ​,2).2). When the lateral wall is damaged, we fill 1 mL of viscous cement after expanding the intravertebral space and removing the balloon. Then we reinsert the balloon into the cement and reinflating it, in order to expand the surrounding cement until it abuts the compromised lateral wall. Finally, conventional cement filling is performed. Fig. 1 Radiographs from a 60-year-old woman with fractures of L2 with anterior and posterior vertebral wall deficiency preoperatively Fig. 2 Postoperative radiographs showed a cement barrier in the anterior wall (white arrows) and a safe distance to posterior wall, no cement leakage was found. A small amount of bone cement was used to prevent anterior leakage, just after the first filling ... In summary, to patients with unstable thoracolumbar burst fractures, regardless of whether the fracture line is located at the anterior, posterior or lateral wall of the vertebral body, bone cement leakage can be prevented by some tips introduced above.

Prevention of thoracolumbar osteoporotic compression fracture with transpedicular intracorporeal bone graft with allogenic bone

Objective To evaluate the clinical efficacy of transpedicular intracorporeal bone graft with allogenic bone in treatment of thoracolumbar osteoporotic compression fracture. Methods A total of 45 patients with thoracolumbar osteoporotic compression fractures were treated with posterior short segment pedicle screw fixation and transpedicular intracorporeal bone graft with allogenic bone. Anteroposte-rior and lateral X-ray photographs were taken before and after operation and at follow up period to determine the ratio of anterior and middle compressed body height to the normal height, the vertebral angle and the superior-inferior endplate angle. The extent of local pain was measured by VAS score. The implant failure was also recorded during follow-up. Results The operative reduction and interbody bone grafting exerted a satisfactory effect on the ratio of anterior and middle body height to the normal height, the vertebral angle and the superior-inferior endplate angle. Local back pain disappeared immediately after surgery in 34 patients out of 38 patients followed up for more than two years. No implant failure was found during follow-up. Conclusions Early treatment with posterior short segment pedicle screw fixation and transpedicular intracorporeal bone graft with allogenic bone can effectively correct local deformity, prevent late vertebral collapse and implant failure and is an ideal treatment method for thoracolumbar osteoporotic compression fracture. Key words: Spinal fractures; Thoracic vertebrae; Lumbar vertebrae; Osteoporosis; Allogenic bone

Posterior short-segment pedicle screw fixation at the injured level for thoracolumbar spine fractures

Objective To discuss indications,operation method and clinical outcome of posterior short-segment pedicle fixation at the injured level for treatment of thoracolumbar spine fractures.Methods A total of 38 patients with thoracolumbar spine fractures were equally randomized to Group A(treated with classic short-segment pedicle screw fixation)and Group B(treated with short-segment pedicle screw fixation at the injured level)based on fixation methods(19 patients per group).Preoperative and postoperative JOA score,segmental lordosis(Cobb' s angle),R value(anterior fractured vertebral body height/mean normal vertebral body height×100%),VSA score and internal fixation condition were assessed and compared clinically.Results All patients were followed up for 6-37 months(mean 20.5 months),which showed no statistical difference upon Frankel scores of two operation modes,while the segmental lordosis,VAS score and R value in Group B were than those in Group A.There occurred nuts loosening in one patient and screw bending in one in Group A.There was no implant breakage,loosening or emersion in Group B.Conclusion Posterior short-segmental fixation at the injured level is an adequate and effective procedure for compression fractures and mild to moderate burst fractures of the thoracolumbar spine. Key words: Spinal fractures; Thoracic vertebrae; Lumbar vertebrae; Short-segmental fixation

Treatment of thoracalumbar fractures with posterior short segment peg-stick system plus pedicle screw fixation

Objective To investigate the value of posterior short segment peg-stick system plus pediele screw fixation in treatment of thoracolumbar fractures. Methods There were 38 patients invol-ving fractures at Tn in three patients, at T_(12) in 11, at L_1 in 15 and at L_2 in nine. There were three pa-tients with simple fractures of vertebral compression, 35 with burst fractures, 33 with thoracolumbar frac-tures combined with paraplegia. The patients with simple fracture of vertebral compression were treated by posterior short-segment peg-stick system plus pedicle screw fixation. While the patients with paraplegia and intraspinal occupancy were treated by posterior decompression, vertebral enlargement and bone graft-ing (between zygopophysis and transverse process) after fixation. Results All patients received a fol-low-up for average 14.5 months, which showed accurate position of pedicle screw and fine contour of the injured vertebra after reduction, with no loosening or breakage of fixators, chronic lumbar pain or loss of the height of fractured vertebra. Of all, 33 patients were accompanied by paresis. There was one patient at Grade A, six at Grade B, 16 at Grade C and nine at Grade D before operation. But there was one pa-tient at Grade A, one at Grade B, five at Grade C, 10 at Grade D and 16 at Grade E. Conclusions For thoracolumbar fractures especially vertebral burst fractures, posterior short segment speg-stick system plus pedicle screw fixation is an ideal treatment method, for it has the following advantages: no obvious loss of the height of the vertebra after operation, protection of the intact intervertebral disc under the in-jured vertebra and minor effect on range of motion of the lumbar vertebrae. Key words: Spinal fractures; Thoracic vertebrae; Lumbar vertebrae; Fracture fixation, internal